Immunostimulatory method

ABSTRACT

This invention relates to a method for treating or preventing a disease by raising an innate immune response in a subject, the method comprising administering to the subject an effective amount of a composition comprising a TLR2 moiety in solution, wherein the TLR2 moiety comprises a TLR2 agonist and wherein the disease is not treated or prevented by a humoral or cellular immune response directed against the TLR2 moiety.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the National Stage of International ApplicationNumber PCT/AU2011/001225, filed Sep. 22, 2011, the disclosure of whichis incorporated herein by reference in its entirety, including allfigures, tables and drawings.

TECHNICAL FIELD

The present invention relates to a novel method for eliciting an innateimmune response in a subject involving the use of a TLR2 moietycomprising a TLR2 agonist.

BACKGROUND

Influenza A virus (IAV) infection causes up to 1 billion infections and300,000-500,000 deaths annually and the global outbreak of the swineH1N1 in 2009 has highlighted the limited anti-viral options available tocope with a pandemic influenza. Although vaccines are available againstthe seasonal IAV epidemics, these vaccines induce antibodies against theever-evolving neuraminidase and hemagglutinin surface proteins of IAVand therefore require annual re-formulation and administration. Moreoverthese vaccines are generally not effective against pandemic outbreakscaused by newly emergent viruses. An alternative is to target theconserved internal regions of IAV. However, the recent pandemic outbreakof a swine H1N1 Influenza A virus has led the quest to discover broadlyprotective vaccines and anti-viral options against pandemic influenza.

The present invention is concerned with the development of a novelapproach to the treatment influenza as well as other infectious diseasesand cancers.

SUMMARY OF THE INVENTION

In a first aspect of the present invention there is provided a methodfor treating or preventing a disease by raising an innate immuneresponse in a subject, the method comprising administering to thesubject an effective amount of a composition comprising a TLR2 moiety insolution, wherein the TLR2 moiety comprises a TLR2 agonist and whereinthe disease is not treated or prevented by a humoral or cellular immuneresponse directed against the TLR2 moiety.

In a second aspect of the present invention there is provided a methodfor treating or preventing a disease caused by an infectious agent, themethod comprising administering to a subject in need thereof aneffective amount of a composition comprising a TLR2 moiety in solution,wherein the TLR2 moiety comprises a TLR2 agonist and wherein the TLR2moiety does not induce a specific cellular or humoral immune responsedirected against the infectious agent.

In a third aspect of the present invention there is provided a methodfor treating or preventing cancer by raising an innate immune responsein a subject, the method comprising administering to the subject atherapeutically effective amount of a composition comprising a TLR2moiety in solution, wherein the TLR2 moiety comprises a TLR2 agonist andwherein TLR2 moiety does not induce a specific cellular or humoralimmune response directed against the cancer.

In a fourth aspect of the present invention there is provided apharmaceutical composition comprising an effective amount of a TLR2moiety in solution together with a pharmaceutically acceptable carrieror excipient for treating or preventing a disease by raising an innateimmune response in a subject, wherein the TLR2 moiety comprises a TLR2agonist and wherein the disease is not treated or prevented by a humoralor cellular immune response directed against the TLR2 moiety.

In a fifth aspect of the present invention there is provided use of aneffective amount of a TLR2 moiety in solution for the manufacture of amedicament for treating or preventing a disease in a subject, whereinthe TLR2 moiety comprises a TLR2 agonist, wherein the TLR2 agonistraises an innate immune response in the subject and wherein the diseaseis not treated or prevented by a humoral or cellular immune responsedirected against the TLR2 moiety.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic representation of lipopeptide vaccinecandidates. Schematic representation of Pam2Cys-based constructs. (A)Pegylated Pam2Cys (Pam2Cys-PEG₁₁) consists of a single Pam2Cys moleculecoupled to undecaethyleneglycol (polyethelene glycol, PEG) via twoscenes. (B) Pam2Cys-based lipopeptide vaccine candidates are composed ofa target CD8⁺ T cell epitope and T helper epitope linked through asingle lysine (K) residue. The Pam2Cys lipid moiety is attached via twoserine residues (Ser) to form a branched peptide structure.

FIG. 2 shows intranasal administration of lipopeptide expands pulmonarycell populations. C57BL/6 mice were inoculated intranasally with 25 nmolof the OT2-P2C-gB₄₉₈₋₅₀₅ lipopeptide or 25 nmol of the peptideOT2-gB₄₉₈₋₅₀₅ (lacking Pam2Cys) and characterisation of the lung cellpopulations was performed at the indicated time points (n=3/group/timepoint). (A) The total number of lung cells is shown. Symbols representthe mean cell count and the error bars indicate the SEM, #=P<0.01 vs.day 0. (B) The composition of lung cells is shown. Each bar representsthe mean cell count (n=3) and the error bars indicate the SD, *=P<0.05vs the cell population at day 0. Statistical analyses were carried outusing one-way ANOVA analysis and post-hoc Dunnett's multiple comparisontest. A repeat experiment yielded similar results.

FIG. 3 shows Pam2Cys-based lipopeptides enhance the clearance of IAV.(A) Mice were inoculated with saline, IAV-LP (containing an IAV-derivedepitope) or non-IAV-LP and challenged at day 3 (upper panel) or day 7(lower panel) following lipopeptide inoculation with 10^(4.5) pfu ofMem71 (H3N1) influenza virus (n=3-5/group). Lung viral titres wereassessed at day 5 of infection and are shown for BALB/c (⋄), C57BL/6 (□)and HHD (◯) mice. Symbols represent the titre obtained from anindividual mouse and the line indicates the mean virus titre of thegroup. (B) The percentage of viral clearance relative to the salinecontrol is shown above the lipopeptide groups. IAV-specific CD8⁺ T cellresponses were detected from C57BL/6 mice challenged with Mem71 on day 7after LP inoculation. On day 5 of challenge PA₂₂₄₋₂₃₃-specific CD8⁺ Tcells were detected from the spleen using an intracellular stainingassay for IFN-γ and TNF-α. Bars indicate the mean cytokine-specificresponse in each group and the error bars indicate the SD. *=P<0.05,**P<0.01 vs Saline (one-way ANOVA analysis and post-hoc Dunnett'smultiple comparison test.

FIG. 4 shows PamCys-based lipopeptides reduce the impact of highlypathogenic IAV infection. Upper panels: Kaplan-Meier plot showingsurvival of C57BL/6 mice (left hand) and HHD mice (right hand)inoculated intranasally with saline, IAV-LP or non-IAV-LP (n=5/group)and challenged 7 days later with H1N1 PR8 virus. Lower panels: Changesin body weight following infection. Symbols indicate the mean and errorbars indicate SEM. These results were reflected in an independent repeatof the experiment in both mouse strains.

FIG. 5 shows Pam2Cys on the pulmonary cytokine environment. C57BL/6 micewere administered 20 nmol of Pam2Cys-PEG₁₁ (P2C-PEG₁₁) or 50 μl ofsaline (i.n) and the concentration of cytokines in the Bronchoalveolarlavage (BAL) fluid was determined at day 3 (D3) or 7 (D7)post-administration using a BD™ Cytometric Bead Array. Bars representthe mean response of each group (n=3) and error bars indicate the SD,*=P<0.05; **P<0.01; ***=P<0.001 vs. Saline and Naive groups (One-wayANOVA and post hoc Tukey's multiple comparison test).

FIG. 6 shows that Pam2Cys mediates viral clearance. Mice were inoculatedwith saline or 20 nmol of Pam2Cys-PEG₁₁ and challenged 1 (upper panel),3 (middle panel) or 7 (lower panel) days later with 10^(4.5) pfu ofMem71 (H3N1) virus (n=3-5/group). The viral titres were assessed at day5 of infection in BALB/c (⋄), C57BL/6 (□) and HHD (◯) mice. Symbolsrepresent the titre obtained from an individual mouse and the lineindicates the mean virus titre of the group, *=P<0.05 vs Saline(unpaired student's t-test). The percentage of viral clearance relativeto the saline group is indicated above the Pam2Cys response.

FIG. 7 shows that intranasal Pam2Cys administration expands cellsubpopulations in the lung. C57BL/6 mice were administered 20 nmol ofpegylated Pam2Cys (P2C-PEG₁₁) or 50 μl of saline (i.n) and the pulmonarycell populations were characterised 72 hr post-administration. Barsrepresent the mean response of each group (n=3) and error bars indicatethe SD, *=P<0.05; vs. saline group (unpaired student's t-test).

FIG. 8 shows that Pam2Cys protects against virulent LAV Infection.C57BL/6 mice were inoculated intranasally with saline or 20 nmol ofpegylated Pam2Cys (P2C-PEG₁₁) (n=5/group) and challenged 7 days laterwith 200 pfu H1N1 PR8 virus. One group of mice received 20 nmol ofP2C-PEG₁₁ and was challenged 72 hr later. The changes in body weightfollowing infection are shown as a percentage of the original weight.Symbols indicate the mean and error bars indicate SEM. These resultswere reflected in an independent repeat of the experiment.

FIG. 9 shows that Pam2Cys prophylaxis reduces viral loads and contacttransmission of influenza. BALB/c mice were inoculated with saline(white bars) or 20 nmol of pegylated Pam2Cys (P2C-PEG₁₁) (grey bars) andchallenged 7 days, 5 days, 72 hr or 24 hr later with 10^(4.5) pfu ofUdorn (H3N2) virus (n=2/group). These mice were designated as thespreader mice. Twenty-four hours following challenge, the spreader micewere co-housed with naïve recipient mice. Following 24 hr of co-housing,the spreader mice were removed and nasal turbinates, trachea and lungswere removed and viral titres were determined (upper panel). Organs fromthe recipient mice were harvested 3.5 days following exposure to thespreader mice and viral titres were assessed (lower panel). The white orgrey arrows indicate successful contact-mediated transmission from therespective treatment group to the co-housed recipients.

FIG. 10 shows that PEG-Pam2Cys protects in a single dose against IAVwhen delivered intranasally. Mice were prophylactically administeredPEG-Pam2Cys (20 nmol) via the intranasal (i.n), subcutaneous (s.c) orintravenous (i.v) routes and 3 days later challenged with a lethal doseof PR8 virus. The mice were then monitored over an 8 day period post-PR8for body weight and survival and culled at a humane end-point.

FIG. 11 shows that several Pam2Cys variants also confer protectionagainst IAV challenge. Mice were prophylactically administered 20 nmolof various Pam2Cys containing constructs via the intranasal routes and 3days later challenged with a lethal dose of PR8 virus. The mice werethen monitored over an 8 day period post-PR8 for body weight (A) andsurvival (B). The reduction in body weight seen in the Saline group wasstatistically significant (P>0.01) when compared to each of the othertreatment groups.

FIG. 12 shows that PEG-Pam2Cys is effective when given in a repeateddose. Balb/c mice were administered a single dose of PEG-Pam2Cys, or twodoses of PEG-Pam2Cys three weeks apart and then challenged with PR8three days after the second dose. The mice were then monitored over an 8day period post-challenge for body weight and survival and culled on day7 post-PR8 for assessment of lung viral load. The reduction in bodyweight seen in the Saline group was statistically significant (P<0.01)when compared to each of the other treatment groups (A). Viral loads inmice treated with PEG-Pam2Cys were substantially lower than in micewhich received saline only (B).

FIG. 13 shows that lower doses of PEG-Pam2Cys are also effective. Micewere prophylactically treated with lower doses of PEG-Pam2Cys at 2, 5and 10 nmol (c.f. 20 nmol) and challenged 3 days later with a lethaldose of PR8 virus. The mice were monitored over an 18 day periodpost-challenge for change in body weight and survival and culled at ahumane end-point. Mice within the Saline group did not survive beyondday 8 post-PR8 challenge.

FIG. 14 shows that protection against IAV challenge is not dependant onIFN-γ or type 1 interferons (i.e. IFN-α). Mice deficient in IFN-γ(B6.IFN-γ−/−) (A) or the Type 1 interferon receptor (IFNAR−/−) (B) wereprophylactically administered 20 nmol of PEG-Pam2Cys (i.n.) and 3 dayslater challenged with a lethal dose of PR8 virus. These mice wereprotected against the weight loss and lethality associated with PR8infection. The B6.IFN-γ−/− cohort was culled on day 5, when the salinegroup reached a humane end point.

FIG. 15 shows that PEG-Pam2Cys is effective as a therapeutic agent.Balb/c mice were challenged i.n with 10^(4.5) PFU of Udorn virus and 4hours later administered 20 nmol PEG-Pam2Cys (i.n.). Two days later,animals were culled and viral loads were determined in the nose,oropharynx, trachea and lung.

FIG. 16 shows that PEG-Pam2Cys is effective as an anti-bacterial agent.C57BL/6 mice were pre-treated (i.n) with 20 nmol of PEG-Pam2Cys and 3days later challenged with 1×10⁶ CFU of L. pneumophila (JR32 Δflastrain). Mice were monitored daily after intranasal challenge with L.pneumophila and the bacterial load in the lungs of mice was assessed 1,2 and 3 days after challenge (A). Each symbol represents the meanbacterial load obtained at each time point and the error bars depict thestandard deviation (SD). Statistical significance is denoted by (p<0.05)which was obtained using a student's t-test comparing saline andPEG-Pam2Cys treatment groups. The mean percentage bacterial reduction inrelation to the saline group is shown above each symbol. To demonstratethe window of PEG-Pam2Cys protection, mice were pre-treated withPEG-Pam2Cys 3 days (B) or 7 days (C) prior to challenge with L.pneumophila. Bacterial load at day 3 post-infection is shown in FiguresB and C.

DETAILED DESCRIPTION

Throughout this specification, unless the context requires otherwise,the word “comprise”, or variations such as “comprises” or “comprising”,will be understood to imply the inclusion of a stated element or integeror group of elements or integers but not the exclusion of any otherelement or integer or group of elements or integers.

The reference in this specification to any prior publication (orinformation derived from it), or to any matter which is known, is not,and should not be taken as an acknowledgment or admission or any form ofsuggestion that that prior publication (or information derived from it)or known matter forms part of the common general knowledge in the fieldof endeavour to which this specification relates.

All publications mentioned in this specification are herein incorporatedby reference in their entirety.

It must be noted that, as used in the subject specification, thesingular forms “a”, “an” and “the” include plural aspects unless thecontext clearly dictates otherwise. Thus, for example, reference to “anagent” includes a single agent, as well as two or more agents; referenceto “the composition” includes a single composition, as well as two ormore compositions; and so forth.

In this specification the term “TLR2” is intended to mean Toll-LikeReceptor 2 protein. TLR2 is a membrane receptor protein family ofToll-Like Receptors (i.e. “TLRs”) including TLR1, TLR3, TLR4, TLR5,TLR6, TLR7, TLR8 and TLR9. In humans. TLR2 is encoded by the TLR2 gene.TLR2 is expressed on the surface of certain cells and plays afundamental role in pathogen recognition and activation of innateimmunity.

A TLR2 agonist is an agent that binds Toll-like receptor 2. The TLR2agonist may bind TLR2 as a homodimer or heterodimer.

The present invention is predicated on the observation that a TLR2agonist such as S-[2,3-bis(palmitoyloxy)propyl]cysteine (Pam2Cys)demonstrates the ability to raise an innate immune response in a subjectand, in particular, elicit a prophylactic and therapeutic effect againstan infectious agent such as a virus (e.g., Influenza A) and bacteria(e.g., L. pneumophila) in a non-antigen specific manner.

Thus, in a first aspect of the present invention, there is provided amethod for treating or preventing a disease by raising an innate immuneresponse in a subject, the method comprising administering to thesubject an effective amount of a composition comprising a TLR2 moiety insolution, wherein the TLR2 moiety comprises a TLR2 agonist and whereinthe disease is not treated or prevented by a humoral or cellular immuneresponse directed against the TLR2 moiety.

In some embodiments, the TLR2 agonist is a lipopeptide or comprises alipid moiety.

An exemplary lipopeptide in accordance with this embodiment of thepresent invention is the lipopeptide “Pam₂Cys”. One of skill in the artwould understand that the term “lipopeptide” means any composition ofmatter comprising one or more lipid moieties and one or more amino acidsequences that are conjugated. “Pam₂Cys” (also known asdipalmitoyl-S-glyceryl-cysteine or S-[2,3 bis(palmitoyloxy)propyl]cysteine has been synthesised and corresponds to the lipid moietyof MALP-2, a macrophage-activating lipopeptide isolated from Mycoplasmafermentans. Pam₂Cys is known to be a ligand of TLR2.

Pam2Cys has the structure;

Another exemplary lipopeptide is the lipoamino acidN-palmitoyl-S-[2,3-bis(palmitoyloxy)propyl]cysteine, also known asPam3Cys or Pam3Cys-OH is a synthetic version of the N-terminal moiety ofBraun's lipoprotein that spans the inner and outer membranes of Gramnegative bacteria. Pam3Cys has the following structure:

U.S. Pat. No. 5,700,910 describes severalN-acyl-S-(2-hydroxyalkyl)cysteines for use as intermediates in thepreparation of lipopeptides that are used as synthetic adjuvants, Blymphocyte stimulants, macrophage stimulants, or synthetic vaccines.U.S. Pat. No. 5,700,910 also teaches the use of such compounds asintermediates in the synthesis of Pam3Cys-OH and of lipopeptides thatcomprise this lipoamino acid or an analog thereof at the N-terminus.

Other lipid moieties which may be used to target cell surface TLRsinclude palmitoyl, myristoyl, stearoyl, lauroyl, octanoyl, or decanoyl.

In addition to Pam2Cys and Pam3Cys, the present invention alsocontemplates the use of Set2Cys, Lau2Cys and Oct2Cys according to thepresent invention. Those skilled in the art will be aware that Set2Cysis also known as S-(2,3-bis(stearoyloxy)propyl)cysteine ordistearoyl-5-glyceryl-cysteine; that Lau2Cys is also known asS-[2,3-bis(lauroyloxy)propyl]cysteine or dilauroyl-S-glyceryl-cysteine);and that Oct2Cys is also known as S-[2,3-bis(octanoyloxy)propyl]cysteineor dioctanoyl-S-glyceryl-cysteine).

Other suitable TLR2 agonists include, but are not limited to, synthetictriacylated and diacylated lipopeptides, FSL-I (a synthetic lipoproteinderived from Mycoplasma salivarium I), Pam₃Cys (tripaltnitoyl-S-glycerylcysteine) andS-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-N-palmitoyl-(R)-cysteine, where“Pam₃” is “tripalmitoyl-S-glyceryl”. Derivatives of Pam₃Cys are alsosuitable TLR2 agonists, where derivatives include, but are not limitedto,S-[2,3-bis(palmitoyloxy)-(2-R,S)-propyl]-N-palmitoyl-(R)-Cys-(S)-Ser-(Lys)₄-hydroxytrihydrochloride;Pam₃Cys-Ser-Ser-Asn-Ala; PaM₃Cys-Ser-(Lys)₄; Pam₃Cys-Ala-Gly;Pam₃Cys-Ser-Gly; Pam₃Cys-Ser; PaM₃CyS-OMe; Pam₃Cys-OH; PamCAG,palmitoyl-Cys((RS)-2,3-di(palmitoyloxy)-propyl)-Ala-Gly-OH; and thelike. Another non-limiting examples of suitable TLR2 agonists arePam₂CSK₄ PaM₂CSK₄ (dipalmitoyl-S-glyceryl cysteine-serine-(lysine)₄; orPam₂Cys-Ser-(Lys)₄) is a synthetic diacylated lipopeptide. Othersynthetic TLRs agonists include those described, e.g., in Kellner et al.(1992, Biol. Chem. 373:1:51-5); Seifer et al. (1990, Biochem. J,26:795-802) and Lee et al. (2003, J. Lipid Res., 44:479-486).

As will be understood by persons skilled in the art, TLR2 agonists aretypically non-polar and, accordingly, while being soluble in non-polarsolvents, are only sparingly soluble in polar and aqueous solvents.Where it is desired to use the TLR2 agonist in a polar or aqueoussolvent, the TLR2 agonist may be conjugated with a solubilising agent.

A solubilising agent may include one, or more than one, solubilisingagent which may be conjugated to TLR2 agonist in order to improve thesolubility of the TLR2 moiety. The solubilising agent will generally bea polar moiety which increases the solubility of the TLR2 moiety inpolar or aqueous solvents.

In yet a further embodiment of the present invention, the solubilisingagent includes one or more of the group consisting of “PEG” (orpolyethyleneglycol) and a polar polypeptide such as “R4”, ahyper-branched tetra arginine complex; “H4”, a hyper-branched tetrahistidine complex; “H8”, a linear peptide containing histidinc residues;and “E8” a linear peptide containing glutamate residues. Other linearand branched lipid solubilising agents are also envisaged, including ahyper-branched peptide containing glutamate residues (see, e.g.,“branched E8”, below). In yet a further embodiment of the presentinvention, the solubilising agent includes PEG and one or more of thegroup consisting of R4, H4, H8 and E8 (linear or branched). R4, H4, H8and E8 have been previously described in PCT/AU2009/000469(WO/2010/115230) and have the following structures:

A person skilled in the art will appreciate that the present inventionis not limited to the particular solubilising agents exemplified, andthat other suitable solubilising agents known in the art may be used inaccordance with the present invention, such as carbohydrates.

The way in which the one or more solubilising agents may be conjugatedto a lipid according to the present invention would be well known to aperson skilled in the art. For example, conjugation via Fmoc chemistry,through a disulfide or a dioether bridge, or via oxime chemistry isenvisaged. In a particular embodiment of the present invention, asoluble form of Pam2Cys was prepared by addition ofO—(N-Fmoc-2-aminoethyl)-O′-(2-carboxyethyl)-undecaethyleneglycol(Fmoc-PEG₁₁-OH, Merck Ltd) to Pam2Cys. This resulted in the formation ofa pegylated form of the lipid, Pam2Cys-PEG₁₁ which is then suitable foradministration to a subject.

In a particularly preferred form according to the present invention, theTLR2 moiety comprises a conjugate comprising Pam2Cys conjugated to PEG.

As previously indicated, the present inventors have made the surprisingobservation that Pam2Cys demonstrates prophylactic and therapeuticactivity against infection by an infectious agent such as a virus (e.g.,Influenza A) or bacteria (e.g., L. pneumophila) in a non-antigenspecific manner. For instance, when delivered intranasally, a singledose of soluble Pam2Cys provided immediate and significant protectionagainst heterologous subtypes of influenza A infection in C57BL/6,BALB/c and HHD mice as demonstrated by up to 99% reduction in viralloads following mild H3N1 infection, and significantly reduced themorbidity and mortality associated with highly pathogenic H1N1infection.

The inventors have also found that administering a TLR2 agonist inaccordance with the methods of the present invention elicits an innateimmune response in a subject in the absence of any co-administered TLRagonist, including a TLR9 agonist. Thus, in some embodiments, thecomposition according to the present invention does not comprise a TLR9agonist.

The inventors have shown that the TLR2 agonist according to the presentinvention can raise a non-antigen specific, innate immune response in asubject. This has been demonstrated by experiments involvingadministration of a TLR2 moiety comprising one or more peptide antigens,wherein the peptide antigen is “irrelevant” to the disease to be treatedor prevented. The term “irrelevant” as used herein is intended to meannot capable of raising a humoral or cellular response to a specificantigen or antigens and, in the context of the present invention, doesnot raise a humoral or cellular immune response directed against theTLR2 moiety.

Accordingly, the TLR2 agonist according to the present invention mayfurther comprise one or more irrelevant peptide antigens for treatmentor prevention of a disease including, but not limited to, T-helperepitopes and/or cytotoxic T-lymphocyte (CTL) epitopes. It is importantto bear in mind that since the TLR2 moiety according to the presentinvention can generate an innate immune response in the subject in anon-antigen specific manner, the skilled person would appreciate thatthe TLR2 moiety can comprise one or more peptide antigens that will beirrelevant to the disease to be prevented or treated or the TLR2 moietycan be used in the absence of one or more peptide antigens.

By way of illustration, the present invention demonstrates that in thetreatment of IAV, a TLR2 moiety comprising one or more “irrelevant”peptide antigens demonstrated the same ability to raise a non-antigenspecific/innate immune response following administration of the moietyas the identical TLR2 agonist but without the peptide antigen attachedthereto. In these experiments, the inventors used a compositioncomprising a TLR2 moiety, wherein the TLR2 moiety comprised a TLR2agonist (e.g., Pam2Cys), a T-helper epitope (OT2) and/or the cytotoxic Tlymphocyte epitope Herpes Simplex virus 1-derived CD8+ T cell epitope(refer to Table 1). Both epitopes are irrelevant to IAV. The inventorshave thus shown that the TLR2 moiety according to the present inventioncan raise a non-antigen-dependent, innate immune response in a subjectto which it is administered.

Thus, in another aspect of the present invention, there is provided amethod for treating or preventing a disease caused by an infectiousagent, the method comprising administering to a subject in need thereofan effective amount of a composition comprising a TLR2 moiety insolution, wherein the TLR2 moiety comprises a TLR2 agonist and whereinthe TLR2 moiety does not induce a specific cellular or humoral immuneresponse directed against the infectious agent.

In some embodiments, the present invention provides a method for raisingan innate immune response in a subject which has an immediate anti-viraleffect against a virus following infection. In particular, this meansthat administration of the TLR2 moiety according to the presentinvention may have a prophylactic effect following viral infection, andin particular influenza A infection, in the subject. Accordingly, in afurther embodiment according to the present invention, administration ofthe TLR2 receptor agonist may be used in the prophylaxis of diseasecaused by an infectious agent in the subject. In this way, the methodsaccording to the present invention may be used to elicit an innateimmune response in the prophylaxis of infection by infectious agents,including, but not limited to, Influenza A virus (IAV), Hepatitis Cvirus (HCV), Mycobacterium tuberculosis, L. pneumophila and infectiousagents known to cause cancer.

The present invention also contemplates a method for raising an innateimmune response in a subject that has already been infected or colonisedby an infectious agent. In particular, this means that administration ofthe composition according to the present invention may have atherapeutic effect following infection or colonisation by an infectiousagent in the subject. Accordingly, in a further embodiment,administration of the composition according to the present invention maybe used in the treatment of disease caused by an infectious agent in thesubject.

The inventors have also shown that pre-treated a subject with a TLR2moiety according to the present invention can significantly reducedbacterial loads in the lung and trachea following intranasal challengewith bacteria, even where infection by bacteria occurs 7 days afteradministration of the TLR2 moiety. Thus, in some embodiments, theinfectious agent is a bacterium. The bacterium can be an intracellular,a gram positive, or a gram negative bacterium. In one embodiment, thebacterium includes, but is not limited to Staphylococcus, Bacillus,Francisella, Yersinia, Legionella pneumophila and Mycobacteriumtuberculosis. In one embodiment, the infectious agent is Mycobacteriumtuberculosis. In another embodiment, the infectious agent is Legionellapneumophila.

In some embodiments, the infectious agent is the cause of a secondaryinfection in the subject (e.g., pneumonia). Thus, the present inventionalso provides a method for treating or preventing a secondary infectionin a subject by raising an innate immune response, the method comprisingadministering to the subject an effective amount of a compositioncomprising a TLR2 moiety in solution, wherein the secondary infection isnot treated or prevented by a humoral or cellular immune responsedirected against the soluble TLR2 moiety.

The present inventors have also demonstrated that, when administeredprophylactically, a composition comprising a TLR2 moiety according tothe present invention is able to provide immediate protection againstmild and pathogenic infection by an infectious agent such as Influenza Aand that this protection is associated with the an influx of innateimmune mediators into the lung. This anti-viral activity is notantigen-specific.

The present invention also contemplates the use of a TLR2 moiety asdefined herein for treating cancer in a subject. Accordingly, in anotheraspect of the present invention there is provided a method for treatingor preventing cancer by raising an innate immune response in a subject,the method comprising administering to the subject a therapeuticallyeffective amount of a composition comprising a TLR2 moiety in solution,wherein the TLR2 moiety comprises a TLR2 agonist and wherein TLR2 moietydoes not directly induce a specific cellular or humoral immune responsedirected against the cancer. In some embodiments, administration of theTLR2 moiety inhibits the growth or spread of cancer.

The skilled person would recognise that the cancer may or may not becaused by an infectious agent. Accordingly, established cancers notcaused by infectious agents may also be treated in accordance with themethods of the present invention. For example, the TLR2 moiety may beadministered directly to the site of a tumour causing cancer in asubject, so as to induce an innate immune response in the subject.Direct administration of the TLR2 agonist to the site of tumour causingcancer may involve recruitment of cells of the innate immune system(e.g. neutrophils, macrophages and cytokines) to the site of the tumour.Thus, in some embodiments, the composition is administered directly tothe site of the tumour causing cancer. The term “tumour” is intended tomean a neoplasm or a solid lesion formed by an abnormal growth of cells(sometimes termed “neoplastic”). It is important to bear in mind thatthe term tumour is not necessarily synonymous with cancer. A tumour canbe benign, pre-malignant or malignant, whereas cancer is by definitionmalignant, however, in many cases a tumour is associated with cancer. Asused herein the term “cancer” refers to a group of diseases anddisorders that are characterized by uncontrolled cellular growth (e.g.formation of tumour) without any differentiation of those cells intospecialized and different cells.

The term “subject” as used herein refers to an animal, in particular amammal and more particularly a primate including a lower primate andeven more particularly, a human who can benefit from the medicalprotocol of the present invention. A subject regardless of whether ahuman or non-human animal or embryo may be referred to as an individual,subject, animal, patient, host or recipient. The present invention hasboth human and veterinary applications. For convenience, an “animal”specifically includes livestock animals such as cattle, horses, sheep,pigs, camelids, goats and donkeys. With respect to horses, these includehorses used in the racing industry as well as those used recreationallyor in the livestock industry. Examples of laboratory test animalsinclude mice, rats, rabbits, guinea pigs and hamsters. Rabbits androdent animals, such as rats and mice, provide a convenient test systemor animal model as do primates and lower primates. In some embodiments,the subject is human.

The composition according to the present invention is to be administeredin an effective amount. The terms “effective amount” and“therapeutically effective amount” of a TLR2 moiety, as used herein,mean a sufficient amount to provide in the course the desiredtherapeutic or physiological effect in at least a statisticallysignificant number of subjects. Undesirable effects, e.g. side effects,are sometimes manifested along with the desired therapeutic effect;hence, a practitioner balances the potential benefits against thepotential risks in determining what is an appropriate “effectiveamount”. The exact amount required will vary from subject to subject,depending on the species, age and general condition of the subject, modeof administration and the like. Thus, it may not be possible to specifyan exact “effective amount”. However, an appropriate “effective amount”in any individual case may be determined by one of ordinary skill in theart using only routine experimentation. In some embodiments, aneffective amount for a human subject lies in the range of about 0.1nmol/kg body weight/dose to 1 mol/kg body weight/dose. In someembodiments, the range is about 1 nmol to 1 mol, about 1 μmol to 1 mol,1 μmol to 500 μmol, 1 μmol to 250 μmol, 1 μmol to 50 μmol, or 1 nmol to1 μmol/kg body weight/dose. In some embodiments, the range is about 0.08μmol to 0.11 μmmol/kg body weight/dose of the TLR2 moiety. Dosageregimes are adjusted to suit the exigencies of the situation and may beadjusted to produce the optimum therapeutic dose. For example, severaldoses may be provided daily, weekly, monthly or other appropriate timeintervals.

The terms “treatment” or “treating” include, but are not limited to, (i)slowing or arresting the progression of disease, (ii) partiallyreversing the progression of disease and (iii) completely reversing theprogression of disease (i.e., curing the disease). The terms “prevent”or “preventing” should not be construed as being limited to the completeprevention of disease (i.e., causing the disease not to develop), butmay include minimizing the progression of disease, for example, wherethe disease occurs with less intensity or progresses at a slower rate ina subject as a result of the prophylactic administration of thecomposition according to the present invention.

The composition according to the invention may be administered in asingle dose or a series of doses. While it is possible for the conjugateto be administered alone, it is preferable to present it as acomposition, preferably as a pharmaceutically composition. Theformulation of such compositions is well known to those skilled in theart. The composition may contain any pharmaceutically acceptablecarriers, diluents or excipients. Suitable dosage amounts and dosingregimens can be determined by the attending physician and may depend onthe particular condition being treated, the severity of the condition aswell as the general age, health and weight of the subject.

By “pharmaceutically acceptable” carrier, excipient or diluent is meanta pharmaceutical vehicle comprised of a material that is notbiologically or otherwise undesirable, i.e. the material may beadministered to a subject along with the selected conjugate withoutcausing any or a substantial adverse reaction. Carriers may includeexcipients and other additives such as diluents, detergents, colouringagents, wetting or emulsifying agents, pH buffering agents,preservatives, and the like. Carriers may also include all conventionalsolvents, dispersion media, fillers, solid carriers, coatings,antifungal and antibacterial agents, dermal penetration agents,surfactants, isotonic and absorption agents and the like. It will beunderstood that the compositions of the invention may also include othersupplementary physiologically active agents.

Accordingly, the present invention also provides a pharmaceuticalcomposition comprising an effective amount of a TLR2 moiety in solutiontogether with a pharmaceutically acceptable carrier or excipient fortreating or preventing a disease by raising an innate immune response ina subject, wherein the TLR2 moiety comprises a TLR2 agonist and whereinthe disease is not treated or prevented by a humoral or cellular immuneresponse directed against the TLR2 moiety.

The compositions of the present invention may be administered by anymeans known to those skilled in the art, including, but not limited to,intranasally, orally and intravenously. In some embodiments, thecompositions are administered intranasally.

The present invention also contemplates the use of an effective amountof a TLR2 moiety in solution for the manufacture of a medicament fortreating or preventing a disease in a subject, wherein the TLR2 moietycomprises a TLR2 agonist, wherein the TLR2 agonist raises an innateimmune response in the subject and wherein the disease is not treated orprevented by a humoral or cellular immune response directed against theTLR2 moiety. Those skilled in the art will appreciate that the inventiondescribed herein in susceptible to variations and modifications otherthan those specifically described. It is to be understood that theinvention includes all such variations and modifications which fallwithin the spirit and scope. The invention also includes all of thesteps, features, compositions and compounds referred to or indicated inthis specification, individually or collectively, and any and allcombinations of any two or more of said steps or features.

Certain embodiments of the invention will now be described withreference to the following examples which are intended for the purposeof illustration only and are not intended to limit the scope of thegenerality hereinbefore described.

Examples

Materials and Methods

Peptide and lipopeptide synthesis, purification and authentication.Lipopeptide and peptide synthesis was carried out by conventional solidphase synthesis using Fmoc (9-fluorenylmethoxy carbonyl) chemistrythroughout. Peptides were assembled automatically using a SymphonyMultiplex synthesiser (Protein Technologies Inc, Arizona, USA) or aLiberty synthesiser (CEM, North Carolina, USA) which uses microwavetechnology to facilitate production of high fidelity peptide sequences.Peptides and lipopeptides were purified by reversed phase highperformance liquid chromatography and the authenticity of products wasdetermined by mass spectrometry. The procedures used for peptideassembly, purification and characterization have been described indetail elsewhere (1, 2, 3). A soluble form of Pam2Cys was prepared byaddition ofO—(N-Fmoc-2-aminoethyl)-O′-(2-carboxyethyl)-undecaethyleneglycol(Fmoc-PEG₁₁-OH, Merck Ltd) to Pam2Cys. This resulted in the formation ofa pegylated form of the lipid, Pam2Cys-PEG₁₁. The epitopes included inthe lipopeptide constructs and the individual lipopeptide compositionsare shown in Table 1.

Animals. 6-8 week old C57BL/6, BALB/c, B6.IFN-γ−/−, B6.IFNAR−/− and HHDnude and female mice were used. HHD “knock out” mice express a chimericmonochain of the α1-α2 domains of HLA-A2.1 and α3 and cytoplasmic andtransmembrane domains of H-2D^(b). These mice are constructed on adouble knock out H-2D^(b)−/−β2m−/− mouse, that fails to expressserologically detectable murine H-2D^(b) molecules (4, 5). HHD mice weredeveloped at the Institut Pasteur, Paris, and were kindly supplied bythe Queensland Institute for Medical Research. Mice were bred andmaintained in the Animal House Facility, Department of Microbiology.B6.IFN-γ^(−/−) mice are deficient in interferon-γ and B6.IFNAR^(−/−)mice do not possess the type 1 interferon receptor. TLR2-deficient micewere kindly provided by Dr Shizuo Akira, Osaka University. Allprocedures involving mice were approved by The University of MelbourneAnimal Experimentation Ethics Committee.

Inoculation procedure. Mice were anaesthetizated by Penthrane™ orIsoflurane inhalation and inoculated with 25 mmol of lipopeptide, 25nmol of the non-lipidated peptide or 2-20 nmol Pam2Cys containingconstructs by the intranasal route. Pam2Cys containing constructs andlipopeptides and peptide were dissolved in saline and administered in avolume of 50 μl while saline control groups received 50 μl of salineonly.

Challenge with influenza a virus. On day 1, 3 or 7 following inoculationwith lipopeptide mice were challenged intranasally with live IAV. Formild IAV infection, mice were administered 10^(4.5) PFU of the H3N1virus, Mem71, a genetic reassortant of A/Memphis/1/71[H3N2]×A/Bellamy/42 [H1N1]. On day 5 of challenge, lungs were harvestedfor determination of viral titres and spleens harvested forcharacterization of the CD8⁺ T cell responses. Challenge with highlypathogenic IAV was carried out using 50 PFU (HHD mice), 200 PFU (C57BL/6mice) or 500 PFU (BALB/c mice) of the HINT virus A/Puerto Rico/8/34(PR8) via the intranasal route. This highly pathogenic virus induces asymptomatic infection characterised by weight loss and dehydration. Micewere monitored daily for signs of morbidity and culled when necessary ata humane end point which was determined using a combination of clinicalsymptoms and degree of weight loss approved by The University ofMelbourne Animal Ethics Committee.

Challenge with Legionella pneumophila bacteria. C57BL/6 mice wereintranasally pre-treated with 20 nmol of PEG-Pam2Cys 3 days prior tointranasal challenge with 1×10⁶ CFU of L. pneumophila (JR32 Δflastrain). The bacterial load in the lungs of mice was assessed 1, 2 and 3days after infection.

Contact Transmission Study. To assess viral transmission in BALB/c mice,“donor” mice (n=2) received 10^(4.5) pfu of the H3N2 Udorn virus(A/Udorn/72) in 50 μl of saline by the intranasal route. One dayfollowing challenge, donor mice were co-housed with naive “recipient”mice (n=3) for 24 hrs after which the donor mice were removed and nasalturbinates, trachea and lungs harvested and assessed for viral titres.Three and a half days following exposure to donor mice, the nasalturbinates, trachea and lungs of recipient mice were harvested forassessment of viral titres. This protocol is based on a contacttransmission model developed by Edcnborough et al (in preparation).

Assessment of viral titres in nasal turbinates, trachea and lungs. Thenasal turbinates, trachea and lungs of mice were homogenized in 3 ml ofRPMI and the titers of IAV virus in the lung supernatants weredetermined using a Medine Darby Canine Kidney (MDCK) Plaque Assay asdescribed previously (6).

Preparation of single-cell suspensions from organs. Following CO₂asphyxiation, the lungs of mice were perfused with 10 ml of PBS via theright ventricle of the heart to remove circulating cells. Lungs were cutinto pieces and subjected to enzymatic digestion with collagenase A (2mg/ml, Roche, Mannheim, Germany) in RPMI for 30 mins. Digested lungfragments were strained through a sieve and treated with 3 ml pre-warmedTris-buffered ammonium chloride solution (ATC) for 2 minutes at roomtemperature in order to lyse erythrocytes. Lung cells were then washedtwice in RP10 (RPMI 1640 medium [Gibco, USA] supplemented with 10% FCS[CSL, Parkville, Australia] 7.5 mM HEPES, 2 mM L-glutamine, 76 μM2-mercaptoethanol, 150 U/ml penicillin, 150 μg/ml streptomycin and 150μM non-essential amino acids [Gibco]. Spleens were collected into 10 mlof RP10 and single cell suspensions prepared by disruption through asieve and then treated with ATC for 5 minutes at 37° C. Cells werewashed twice with RP10 before use. To obtain Bronchoalveolar lavage(BAL) Fluid the mouse tracheas were cannulated with a syringe and theair space was flushed with three separate 1 ml washes of RPMI, and afinal 1 ml rinse of the syringe. The supernatant from the BAL washes wasstored at −70° C. for later cytokine analysis. The supernatant from theBAL washes was stored at −70° C. for later cytokine analysis. Viablecells counted using a haemocytometer and trypan blue dye exclusion.

Characterisation of the pulmonary cytokine environment. Cytokine levelsin the BAL supernatant was determined using a BD™ Cytometric bead array(CBA) (Biosciences) Mouse Inflammation Kit according to the manufacturesinstructions, with the exception that only 2 μl of each capture bead wasused for each 50 μl BAL sample. Standard curves (20-5000 pg/ml) wereprepared for the following cytokines interleukin-6 (IL-6),interleukin-10 (IL-10), monocyte chemoattractant protein-1 (MCP-1),Interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) andinterleukin-12p70 (IL-12p70). Cytokine concentrations were determinedfrom neat, or 1/10 dilutions of the BAL supernatant. Samples wereanalysed using a Becton Dickinson FACSCalibur flow cytometer and FlowJosoftware.

Characterisation of lung cells. 5×10⁵ lung cells were stained withcombinations of the following anti-mouse antibodies; FITC labelledanti-CD11b, PerCP-Cy5.5 Anti-GR-1 (Ly-6G and Ly-6GC), PE-labelledanti-CD11c, APC anti-F4/80, FITC anti-IA/IE class 2, PerCP-Cy5.5anti-CD8, PE anti CD4 (BD Pharminigen). Pulmonary cell subsets wereclassified as follows; Neutrophils: CD11b^(hi), GR1^(hi), CD11c⁻,F4/80⁻; alveolar macrophages: CD11c^(hi), F4/80⁺, CD11b^(int/lo),GR1^(int/lo) and CD11c^(hi), Autofluorescence^(hi); dendritic cells:CD11c^(hi), and MHC Class 2^(hi), GR1^(int); monocytes and interstitialmacrophages: CD11b^(hi), GR1^(int), CD11c^(int/lo)), F4/80⁺; CD8⁺Tcells: CD8⁺; CD4⁺T cells: CD4⁺ (7, 8, 9).

Intracellular cytokine staining (ICS) assay. Single cell suspensions oflung or spleen cells were stimulated with peptide at 1 μs/ml (C57BL/6and BALB/c) or 10 ug/ml (HHD) for 6 hr at 37° C. in the presence of 5μg/ml GolgiPulg (BD Biosciences Pharmingen) 25 U/ml and recombinanthuman IL-2 (Roche, Indianapolis, USA) in a total volume of 200 μl RP10.Cells were stained with PerCP (Cy5.5) labelled with rat anti-mouse CD8αantibody (BD Biosciences Pharmingen) for 30 min on ice. Cells were fixedand permeabilised using the BD Cytofix/Cytoperm kit TM (BD) according tothe manufacturers directions and stained with FITC-labelled anti-IFN-γand APC-labelled anti-TNF-α (BD Biosciences Pharmingen) for 30 min at 4°C. Samples were analysed using a Becton Dickinson FACSCalibur flowcytometer and analysed using FlowJo software.

Statistical analyses. For time point comparisons, a one-way ANOVA(post-hoc Dunnett's multiple comparison test) was used to determinedifferences between the pre-inoculation (Day 0) group to thepost-inoculation (Day 1, 3, 6, 8) groups. For other studies, atwo-tailed unpaired student's t-test or one-way ANOVA (post-hoc Tukey'smultiple comparison test) were used to determine statistical differencesbetween two or more than two groups respectively. A P value of <0.05 wasconsidered significant.

Results

Pam2Cys-based lipopeptide inoculation expands the pulmonary cellpopulations. The effect of Pam2Cys-based lipopeptide on the pulmonarycellular environment was examined in C57BL/6 mice which were inoculatedintranasally with the lipopeptide OT2-P2C-gB₄₉₈₋₅₀₅ containing the Thelper epitope (Th) OT2 and a Herpes Simplex virus 1-derived CD8⁺ T cellepitope (gB₄₉₈₋₅₀₅; see Table 1). The lung resident cell populations inlungs perfused with PBS were characterised using cell flow cytometry.Intranasal inoculation with OT2-P2C-gB₄₉₈₋₅₀₅ elicited a dramaticincrease in the total number of lung cells that reached a maximum on day3 and remained elevated until day 8 (FIG. 2A). In contrast, mice thatreceived the peptide OT2-gB₄₉₈₋₅₀₅ (lacking Pam2Cys) showed nosignificant changes in the total number of cells or proportion of celltypes present in the lungs, pointing towards Pam2Cys as the mediator ofthe cellular influx (FIG. 2A). In lipopeptide-inoculated mice, thecellular infiltrate at day 3 following inoculation, was largely composedof neutrophils and interstitial macrophages (FIG. 2B). Microscopicexamination by Giemsa staining revealed that the neutrophils exhibitedan highly vacuolar phenotype; indicating activation, while the F480⁺monocyte/interstitial macrophage population was found to bepredominantly composed of interstitial macrophages with a large andnucleated morphology with few cells possessing the donut orkidney-shaped nucleus characteristic of monocytes were identified (datanot shown). Although alveolar macrophages (AM) were present at very lowlevels in the steady state lung (day 0), a significant increase in thispopulation was evident following lipopeptide inoculation. Finally, wealso observed increases in the CD4⁺ and CD8⁺ lymphocytes and CD11c^(hi)dendritic-like cells between day 3-8 post-inoculation. An examination ofthe pulmonary cell influx of BALB/c and HHD mice revealed similarpatterns of early neutrophil infiltration followed by expansion of theinterstitial macrophage and CD11b^(hi) alveolar macrophage populations(data not shown).

Pegylated Pam2Cys administration expands pulmonary cell populations.Intranasal administration of pegylated Pam2Cys (P2C-PEG₁₁) also resultedin significant increases in the total lung (includes the lunginterstitium and HAL fluid-containing) populations of neutrophils,interstitial and alveolar macrophages and lymphocytes in C57BL/6 (FIG.7) and BALB/c mice (data not shown). Increased levels of activated IFN-γproducing NK cells and γδ T cells were also observed (FIG. 7).

Pam2Cys prophylaxis is effective against highly pathogenic IAVchallenge. To determine if the anti-viral activity of Pam2Cys iseffective against a virulent strain of IAV, mice that received pegylatedPam2Cys (P2C-PEG₁₁) were challenged 72 hr or 7 days later with a lethaldose of the H1N1 virus PR8. The saline-treated (challenged 72 hr later)mice experienced substantial weight loss, developed clinical symptoms ofinfection and by day 8 all mice had succumbed to the infection (FIG. 8).In contrast the mice pre-treated with PEG-Pam2Cys experiencedsubstantially lower weight loss and all mice survived infection (FIG.8).

Pam2Cys prophylaxis can reduce transmission rates. To determine ifinfluenza infected mice pre-treated with Pam2Cys have a reduced capacityto transmit virus, a mouse model of contact transmission was utilised(Edenborough et al., in preparation). “Donor” mice that were pre-treatedwith PEG-Pam2Cys were challenged at various time points thereafter with10^(4.5) pfu of H3N2 Udorn virus. The results show that Pam2Cysprophylaxis reduces nasal, tracheal and lung viral titres (FIG. 9). Allthe recipient mice that were co-housed with saline-treated donor micebecame infected confirming the ability of the donor mice to transmitvirus. Although mice that had received Pam2Cys 5 or 7 days prior tochallenge transmitted virus to recipient mice, mice that had receivedPam2Cys 24 hrs or 72 hrs prior to virus challenge did not transmit theinfection to co-housed recipient mice.

Intranasal delivery of lipopeptide provides immediate protection againstIAV challenge. To determine whether the pulmonary changes induced byintranasal delivery of lipopeptide could reduce the impact of IAVchallenge, the protective affect of lipopeptide inoculation against amild (H3N1) and highly virulent PR8 (H1N1) IAV viruses was examined.Three strains of mouse were administered lipopeptide containing anIAV-specific CD8⁺ T cell epitope (IAV-LP) restricted to the particularmouse strain or an irrelevant non-IAV-derived CD8⁺ T cell epitope(non-IAV-LP) (Table 1). In all lipopeptides, the CD4⁺ Th cell epitopewas unrelated to influenza virus. (Table 1). While the IAV-LP is capableof inducing CD8⁺ T cell responses to the delivered IAV-derived epitopethe absence of IAV-specific epitopes (CD8⁺ T or CD4⁺) in the non-IAV-LPmeans that IAV-specific responses will not be induced on inoculation.

C57BL/6, BALB/c and MID mice were challenged intranasally with 10^(4.5)PFU H3N1 virus, Mem71, either 3 or 7 days following inoculation witheither IAV-LP or non-IAV-LP and lung viral titres were assessed on day 5of infection. The results in FIG. 3A show that in all strains of mice,inoculation with the IAV-LP as well as the non-IAV-LP resulted insignificant reduction of lung virus titres when compared to animals thatdid not receive lipopeptide. In the non-IAV LP group, viral clearancewas most striking when challenge occurred 3 days after inoculation (FIG.3A).

The absence of IAV-specific epitopes (CD8⁺ T or CD4⁺) in the non-IAV-LPsuggested that the anti-viral activity of non-IAV-LPs is conferred bythe Pam2Cys moiety. To confirm this theory, we examined the presence ofIAV-specific CD8⁺ T cell responses to PA₂₂₄₋₂₃₃) an immunodominantUV-specific target in C57BL/6 mice, and the same epitope included in theIAV-LP but not in non-IAV-LP, In lipopeptide inoculated C57BL/6 mice,only mice that received IAV-LP showed significant levels of IFN-γ⁺ orIFN-γ⁺ TNF-α⁺ PA₂₂₄₋₂₃₃-specific CD8⁺ T cells while neither the salinenor the non-IAV-LP groups elicited detectable responses to theseepitopes (FIG. 3B). This same pattern of T cell responses was observedin the BALD/c and HHD mouse strains. The absence of IAV-specific cellsin mice inoculated with non-IAV-LP demonstrates that the earlyanti-viral effect observed is due to the action of Pam2Cys and not to anaccelerated ability to mount an IAV-specific adaptive immune response.

It should be noted that the non-IAV LP, in contrast to IAV-LP, does notprovide long-term protection associated with the induction ofIAV-specific CD8⁺ T cell responses. Only IAV-LP inoculated BALB/c andC57BL/6 mice exhibited significant levels of viral clearance (98±1% and65±14% (respectively)) if challenged with H3N1 occurs 6-8 weeksfollowing inoculation (data not shown). Therefore, in the absence ofantigen specific responses, the anti-viral activity of non-IAV LPs isreduced with time demonstrating that the we T cell epitope component ofthe lipopeptide is essential to long-term protection with IAV-LPs.

Lipopeptide prophylaxis is effective against highly pathogenic IAVchallenge. To determine if the anti-viral activity of Pam2Cys waseffective against highly pathogenic infection, lipopeptide inoculatedmice were challenged 7 days later with the highly pathogenic H1N1 virus,PR8. Both IAV-LP and non-IAV LP lipopeptide inoculation dramaticallyincreased the survival rate in mice challenged with PR8 (FIG. 4). Whilethe majority of mice inoculated with saline succumbed to infection, 100%of animals inoculated with IAV-LP and 80% of animals inoculated withnon-IAV-LP survived the infection. In addition to improved survivalrates, the degree of weight loss and clinical symptomology that isnormally associated with infection was also reduced in the non-IAV-LPgroup (FIG. 4).

The spectrum of cytokines induced by soluble Pam2Cys. To remove theinfluence of peptide, or epitope-specific responses from the system, weconstructed a soluble form of Pam2Cys by conjugating the normallyinsoluble Pam2Cys to polyethylene glycol (PEG). To identify the impactof Pam2Cys-PEG₁₁ on the pulmonary environment, we measured theconcentration of inflammation-associated cytokines in theBronchoalveolar lavage (BAL) fluid of C57BL/6 mice administered 20 nmolPam2Cys-PEG₁₁ (i.n) by cytometric bead array analysis (FIG. 5). On day 3following administration, we detected significant increases in IL-6,IL-10, MCP-1, TNF-α and IL-12p70 concentrations in Pam2Cys-PEG₁₁inoculated mice in comparison to naive or saline inoculated mice. By day7, the cytokine concentrations in the Pam2Cys-PEG₁₁ group had normalisedto pre-administration levels and did not differ significantly to thenaive group (FIG. 5).

The antiviral activity of Pam2Cys is antigen-independent. To confirmthat the Pam2Cys moiety is mainly responsible for the early anti-viralactivity of lipopeptides, mice were inoculated intranasally with 20 nmolof Pam2Cys-PEG₁₁ and challenged with 10^(4.5) PFU H3N1 virus either 1, 3or 7 days later. The results shown in FIG. 6 demonstrate thatinoculation with Pam2Cys-PEG₁₁ reduces lung viral loads to the sameextent as non-IAV-LP, confirming that the early antiviral activity oflipopeptides observed is mediated by Pam2Cys. Prophylaxis withPam2Cys-PEG₁₁ reduced the viral load following challenge almostimmediately, at day 1 and out to day 7 post-administration, revealingthat at least a 7 day window of protection can be provided byPam2Cys-PEG₁₁ prophylaxis.

Pam2Cys protects against IAV when delivered intranasally in a singledose. Following prophylactic administration of pegylated Pam2Cys(PEG-Pam2Cys) (also referred to herein as Pam2Cys-PEG₁₁ or P2C-PEG₁₁) inmice via the intranasal (i.n), subcutaneous (s.c) or intravenous (i.v)routes and a subsequent challenged with a lethal dose of PR8 virus 3days later, only the mice administered PEG-Pam2Cys intranasally woreprotected against death and weight loss associated with PR8 infection(FIG. 10).

TABLE 1Details of the mouse strains and lipopeptides used in the present inventionCD8⁺ T cell MHC Class I Components Mouse MHC class I target epitopeOrigin of CD8⁺ T cell restricting Components of of non- strain phenotypesequence epitope element IAV-LP IAV-LP C57BL/6 H-2K^(b) H-2D^(b)SSLENFRAYV(10) IAV polymerase A H2-D^(b) OT2^(ii)-P2C^(iii)- (PA₂₂₄₋₂₃₃)PA₂₂₄₋₂₃₃ SSIEFARL(11) glycoprotein B of HSV-1 H2-K^(b) OT2-P2C-(gB₄₉₂₋₅₀₅) gB₄₉₄₋₅₀₅ ^(i)HHD HLA-A2.1 GILGFVFTL(12)IAV M1 protein (M1₅₈₋₆₆) HLA-A2.1 OT2-P2C- OT2-P2C- M1₅₈₋₆₆ ^(iv)gB₄₉₈₋₅₀₅ FMYSDFHFI(13) IAV polymerise A (PA₄₆₋₅₅) OT2-P2C-PA₄₆₋₅₅AIMDKNIIL(14) IAV non-structural protein OT2-P2C- (NS1₁₂₂₋₁₃₀)NS1₁₂₂₋₁₃₀ BALB/c H-2K^(d) H-2D^(d) TYQRTRALV(15, 16) IAV nucleoproteinH2-K^(d) P25^(v)-P2C- P25-P2C- (NP₁₄₇₋₁₅₅) NP₁₄₇₋₁₅₅ PA₂₂₄₋₂₃₃ ^(vi)^(i)HHD mice are a transgenic strain that exclusively express chimericHLA-A2.1 class I molecules ^(ii)OT2 (amino acid sequenceISQAVHAAHAEINEAGR) is a Th epitope from ovalbumin. ^(iii)P2C: Pam2Cys^(iv)An admixture of the three IAV-LPs were administered to HHD miceprior to challenge with the H1N1 PR8. Mice challenged with H3N1 Mem71only received OT2-P2C- M1₅₈₋₆₆. ^(v)P25 (amino acid sequenceKLIPNASLIENCTKAEL) is a promiscuous Th epitope (16) from morbilliviruses. ^(vi)The PA₂₂₄₋₂₃₃ epitope is not recognised by the Class 1restriction molecules present in BALB/c mice.

Multiple Pam2Cys variants confer protection against IAV challenge. Micethat were prophylactically administered 20 nmol of variousPam2Cys-containing constructs via the intranasal routes were protectedagainst weight loss (FIG. 11A) and death (FIG. 11B) following achallenge with a lethal dose of PR8 virus. Mice were also protectedagainst other clinical symptoms associated with PR8 infection (data notshown).

Pam2Cys is effective when given in a repeated dose. Balb/c miceadministered a single dose of PEG-Pam2Cys (or two doses of PEG-Pam2Cysthree weeks apart) were protected against weight loss (FIG. 12B), deathand other the clinical symptoms following a challenge with lethal doseof PR8. Viral loads in PEG-Pam2Cys-treated mice were significantly lowerat the time of culling (FIG. 12A).

PEG-Pam2Cys is effective at lower doses. When mice were prophylacticallytreated with lower doses of PEG-Pam2Cys and challenged 3 days later witha lethal dose of PR8 virus, protection against weight loss and death wasstill achieved in all mice compared to the saline group (FIG. 13).

Protection against IAV challenge is not dependent on IFN-γ or type 1interferons (i.e. IFN-α). Mice deficient in IFN-γ (B6.IFN-γ−/−) or inthe ability to respond to type 1 interferon (such as interferon-α;IFNAR−/−) that were treated with PEG-Pam2Cys were protected against theweight loss and lethality associated with PR8 infection (FIG. 14).

PEG-Pam2Cys is effective as a therapeutic agent. When mice werechallenged with 10^(4.5) PFU of Udorn virus (Influenza A) (i.n.) and 4hours later administered 20 nmol PEG-Pam2Cys (i.n.), reduced viral loadswere found in the nose, oropharynx, trachea and lung. Viral load in thelungs, in particular, showed a Log₁₀4, or 10,000 fold reduction ascompared to the Saline group (FIG. 15).

Pam2Cys is effective as an anti-bacterial agent. When mice werepre-treated with PEG-Pam2Cys (i.n.), they showed significantly reducedlung and trachea bacterial loads following i.n. challenge with L.pneumophila (FIG. 16A). The bacterial load in the lungs peaked on day 2and 3. Reduced bacterial loads can also be achieved up to 7 days afterPEG-Pam2Cys administration and bacterial loads at day 3 post infectionis shown for mice which received PEG-Pam2Cys prophylaxis 3 (FIG. 16B) or7 days (FIG. 16C) before challenge.

Discussion

The crucial role that the innate immune response plays in control ofinfection suggests that early activation of the innate immune systemprior to infection could provide enhanced protection against a challengeby an infectious agent, such as a virus or bacterium. The results ofthis study demonstrated that administration of a soluble TLR2 moietycomprising a TLR2 agonist raises an innate immune response in a subjectto which it is administered, wherein the immune response is non-antigenspecific. Moreover, the pulmonary changes elicited by prophylacticintranasal administration of the composition according to the presentinvention were associated with an increased resistance to subsequentexposure to virus and bacteria, suggesting that such compositions aresuitable as prophylactic agents against viral and bacterial infection,particularly when there is high risk of epidemic or pandemic outbreaks.The prophylactic and therapeutic methods according to the presentinvention also have the advantage of not requiring prior knowledge ofthe infectious agent (or its antigenic components or particular strain)and therefore could be particularly useful, for example, duringinfluenza pandemics. The stability of composition according to thepresent invention, which can be freeze dried and is stable at roomtemperature, also means it is highly suitable for stockpiling inpreparation for a pandemic situation.

REFERENCES

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The invention claimed is:
 1. A method for preventing or treating arespiratory condition associated with one or more viral infectiousagents in a subject, the method comprising: administering to therespiratory tract of the subject a composition comprising a soluble TLR2moiety comprising a TLR2 agonist and a solubilizing agent that increasesthe solubility of the TLR2 agonist in polar or aqueous solvents, therebypreventing or treating the respiratory condition in the subject, whereinthe moiety raises an innate immune response in the subject and does notraise an immune response that is specific for an antigen of the one ormore infectious agents, wherein the composition does not contain apeptide antigen comprising a T-helper epitope, and wherein the TLR2agonist is a lipopeptide.
 2. The method according to claim 1, whereinthe TLR2 agonist is selected from the group consisting ofS-[2,3-bis(palmitoyloxy)propyl]cysteine (Pam₂Cys),N-palmitoyl-S-[2,3-bis(palmitoyloxy)propyl]cysteine (Pam₃Cys),S-[2,3-bis(stearoyloxy)propyl]cysteine,S-[2,3-bis(lauroyloxy)propyl]cysteine, andS-[2,3-bis(octanoyloxy)propyl]cysteine.
 3. The method according to claim2, wherein the TLR2 agonist is Pam₂Cys.
 4. The method according to claim1, wherein the soluble TLR2 moiety comprises polyethyleneglycol (PEG) ora polar polypeptide.
 5. The method according to claim 4, wherein thepolar polypeptide is selected from the group consisting of R4, K4, H4,E8, branched E8and H8.
 6. The method according to claim 4, wherein thesoluble TLR2 moiety comprises polyethyleneglycol (PEG).
 7. The methodaccording to claim 1, wherein the soluble TLR2moiety comprisespolyethyleneglycol (PEG) and any one of R4, K4, H4, E8, branched E8 andH8.
 8. The method according to claim 1, wherein the soluble TLR2moietyis R4Pam2Cys.
 9. The method according to claim 1, wherein the solubleTLR2 moiety is PEG-Pam2Cys.
 10. The method according to claim 1, whereinthe soluble TLR2 moiety is E8Pam2Cys.
 11. The method according to claim1, wherein the soluble TLR2 moiety is H8Pam2Cys.
 12. The methodaccording to claim 1, wherein the composition is administeredintranasally to the subject.
 13. The method according to claim 1,wherein the virus is Influenza A virus (IAV).
 14. The method accordingto claim 1, wherein a TLR9 agonist is not administered.
 15. The methodaccording to claim 1, wherein the soluble TLR2 moiety does not comprisea peptide antigen.
 16. The method according to claim 1, wherein thesoluble TLR2 moiety does not comprise an antigen.
 17. The methodaccording to claim 1, wherein the soluble TLR2 moiety consists of a TLR2agonist conjugated to a solubilizing agent.
 18. The method according toclaim 1, wherein the soluble TLR2 moiety comprises an antigen thatcannot raise a specific immune response to the one or more infectiousagents.
 19. The method according to claim 8, wherein R4Pam2Cys has thestructure:


20. The method according to claim 5, wherein H4Pam2Cys has thestructure:


21. The method according to claim 11, wherein H8Pam2Cys has thestructure:


22. The method according to claim 10, wherein E8Pam2Cys has thestructure:


23. The method according to claim 5, wherein branched E8Pam2Cys has thestructure:


24. The method according to claim 7, wherein the soluble TLR2 moietycomprises polyethyleneglycol (PEG) and R4.
 25. The method according toclaim 24, wherein R4 is present as R4Pam2Cys.
 26. The method accordingto claim 25, wherein R4Pam2Cys has the structure:


27. The method according to claim 1, wherein the subject has alreadybeen infected by the one or more viral infectious agents at the time ofsaid administering, and wherein said administering treats therespiratory condition in the subject.
 28. The method according to claim1, wherein the subject has not yet been infected by the one or moreviral infectious agents at the time of said administering, and whereinsaid administering prevents the respiratory condition in the subject.